1. Field of the Invention
The invention relates to a rotary tool and to cutting head for use in rotary cutting tools.
2. Background Information
Tool couplings for combination tools with exchangeable cutting heads must perform several functions. Firstly, they must have sufficient axial pull-out prevention, so that the cutting head is not pulled out from the carrier during working. Problems may occur in this respect particularly during retraction of the drill when it is being withdrawn from the drilled hole. Furthermore, the tool coupling must ensure highly accurate centering of the cutting head with respect to the axis of rotation. Finally, the tool coupling must also be designed for the transmission of sometimes high torques from the carrier to the cutting head.
In the case of the tool coupling according to WO 2007/107294 A1, the coupling pin has a bone-like, asymmetric configuration and is designed as an elongate coupling pin which is completely enclosed by a web of the coupling receptacle. The asymmetric cross-sectional area designed in the manner of a bone and the enclosure by the peripheral web have the effect of making a high torque transmission possible and at the same time achieving self-centering by the widening at both ends. With regard to the axial pull-out prevention, supplementary screws are provided.
WO 1998/53943 discloses tool couplings of a further kind, in which the torque transmission areas extend radially outward. Additionally provided in the case of the tool coupling disclosed there is a central, further coupling pin, which is formed such that it is offset from the torque areas. The coupling pin is screwed into a corresponding pin receptacle during assembly, thereby forming a dovetail connection with a form fit in the axial direction.
The known coupling systems have the disadvantage that complex geometries and/or supplementary means are required to ensure the three stated main functions, axial securement, torque transfer and centering are accomplished.
In view of such disadvantages, a need exists for improved rotary tools and cutting heads therefore.